Live center



O. E. JANSON Jan. 2, 1951 LIVE CENTER Filed NOV. 8, 1947- Oscar-.Ekiiznson Patented Jan. 2, 1951 LIVE CENTER Oscar Jansen, Providence, 3,. 1-

Application November 8, mt SeriaIN 184,911-

This invention relates, to a. so-called live center or one rotating with the work, and one which is resiliently mounted to. yieldingl-y press against. the end of the work and follow the end of the work should it move axially.

Centers of this general type were previously provided with roller or ball bearings which bearings would axially slide with the center as the center moved to follow the work. Such previous arrangement required an expensive construction and considerable pressure for the relative movement of the bearing.

One of the objects of this invention is to provide a center which will rotate with the work and will axially slide itself relative to the bearing, which takes up the compressive lateral transversely. acting forces which are applied thereto.

More specifically an object of this invention is to permit a relative movement of the center and its axially-acting bearing as distinguished from a major portion of the unit comprising the lateral thrust take-up ball bearing.

Another object of the invention is to simplify the construction throughout so that th same may be made much less expensively than live centers which will accomplish the results of this center which have heretofore been made.

With these and other objects in view, the invention consists of certain novel features of construction as will be more fully described and particularly pointed out in the appended claims.

In the accompanying drawings:

Figure l is a perspective view of the live center;

Figure 2 is a sectional view substantially on line 2-2 of Figure 1; and

Figure 3 is a perspective view of the center alone.

In proceeding with this invention, I provide a casing in which there is fixedly mounted a double row ball hearing which cannot move axially with reference to the unit. A center is slidably mounted in this long double ball bearing and is axially urged outwardly by a spring. Between the spring and the center itself is a thrust bearing to absorb the compressive forces acting in a I longitudinal direction of the center, which bearing will slide with the center in its movement against the resilient acting spring.

With, reference to the drawings, in designates generally a casing which is provided on the end of a tapered arbor H which is formed to be received in some machine part to take it. Casing Ill is provided with an internal bore I2 which fits upon the reduced portion 43 of the arbor II and seats against a shoulder l4 formed by this re! 2 Claims. (Cl, 33 33") duoedportion. The interior, of this reduced per ticn. is. provided with a further b rev 5 forth? purposes which will presently appear. Casing it and the arbor are held o ether by a s t sc ew: which may be threaded into engagement with this reduced portion l3.

At the outer end of the casing there is provided a larger bore l1 forming a shoulder 18 against which along double ball bearing I9 is positioned to absorb the compressive lateral or radial forces. This ball bearing is held snugly against the shoulder l8 by a plate 20 which is provided with screws 2| to hold it in place, and also retain the ball bearing in fixed position against axial movement in either direction.

A center consisting of a conical head 22 and a shank 23 is slidably received in the ball bearing so that the same may have axial movement through this ball bearing. A washer 25 is applied on the end of the shank 23 and held thereto by a screw 26. This washer in turn butts against thrust bearing designated generally 21 which serves to take the longitudinal thrust 0r axial thrust on the center. This thrust bearing is axially movable in the bore 28 between the bores l2 and I! which extends inwardly from the opposite end of the casing, and there is also provided a disk against which the helical spring 29 acts to force the thrust bearing and the center outwardly or to the left as shown in Figure 2. The opposite end of this spring 29 seats in the bore [5 formed in the end of the arbor H.

In operation, as pressure is placed upon the head 22 of the live center, it will be forced inwardly so as to place the spring under compression and if there is any change in the length of the workwhich the live center engages, it may be compensated for by the spring which may be either further compressed or may follow outwardly should the piece of work shorten. The transverse compressive forces will be taken care of by the ball bearing while the longitudinal or axial compressive forces will be taken care o anti-frictionally by the thrust bearing 21. By this arrangement, merely the center itself which is a small part of the structure will move in and out'through the ball bearing and nicely follow the work without the necessity of movement oi. the larger ball bearing or a part thereof which would not be turning or rotating in the casing. A much nicer action is therefore provided by sliding between rotating parts rather than between parts which are not rotating, and the structure is such as to more nicely follow the work.

Lubrication may be provided through the cup 38 having a ball 3| to close it by means of spring 32 or may enter through the radialihole 33.

I claim: v 5

1. A livefcenter unit for a lathe or the like comprising a casing provided with "a bore extending axiallyi therethrough and opening out of both ends thereof, an arbor having end means removably secured in the bore at one end of the casing, an annularanti-friction bearing providing a through concentric aperture fixedly mounted at the other end of the casing and'extending in.

said innerend and positioned against said bearing shoulder; a screw having a; slotted head threaded into said hole with it 'head engaging said washer ito hold the same securedto'said "shank'to provide a stop to limitolutward movement of said shank through saids' bearing aperture, and'm'eans including a spring acting between said arbor and washer to urge said center outwardly, said arbor and spring being removable to afiord access to said screw from one end of said casing for removing said washer to permit removal of the center from its bearing from the other end of the casing without removing said bearing.

2. A live center unit as in claim 1 wherein a ball thrust bearing abutting said washer is interposed between said spring and washer, said bearin having an open center aperture to expose said screw.

' OSCAR E. JANSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 

